Antenna system



Feb. 25, 194-1. J ow I 2,232,693

ANTENNA SYSTEM Filed March 18, 1937 3 Sheets-Sheet 1 INVENTOR JENNINGSB. DOW

ay aw ATTORNEY Feb. 25, 1941. J. B. DOW

ANTENNA SYSTEM Filed March 18, 1957 s Sheets-Sheet 2 INVENTOR JENNINGSB. DOW

ATTORNEY Febyzs, 1941. J. B. DOW

ANTENNA SYSTEM Filed March 18, 1937 3Sheets-Sheet 3 INVENTOR JENNINGS B.DOW

ATTORNEY Patented Feb. 25, 1941' UNITED STATES ANTENNA SYSTEM JenningsB. Dow, United States Navy 7 Application March 18,

6 Claims.

1937, Serial No. 131,687

(Granted under the act of March 3, 1883, as

amended April 30,

My invention relates to antenna, systems in general but moreparticularly to an adjustable antenna system. 7

One of the objects of my invention is to provide an efilcient adjustableantenna for radio sending and receiving stations.

Another object of my invention is to provide a simple and inexpensivemeans for adjusting my antenna from a distance.

A still further object of my invention is to provide a simplecombination of transmitter (or receiver), transmission line andadjustable anterms. to produce a highly efficient system as a whole.Other and further objects of my invention will be apparent from thespecification. The present invention is generically similar to thatcovered by my copending application Serial Number 131,686, filed March18, 1937.

For simplicity, my invention will be described with particular referenceto its use for radio transmission. This simplification is not intendedto restrict its scope, since it is equally applicable to receivingsystems. Moreover, while the transmission lines which I shall describein the preferred embodiment of my invention, are of the concentric type,it will be understood that any other suitable type of line may be used.For example, an open type line may be employed by making one or bothconductors in tubular form for supplying gas pressure to operate theantenna.

Fig. 1 shows one form of my adjustable antenna in which the adjustableradiator element is in efiect a continuation of the inner conductor of aconcentric transmission line.

Figs. 1a and 1b are cross sections taken on lines a--a and b-b,respectively, Fig. 1.

Fig, 2 shows another form of my antenna in which the adjustable radiatorelement is a continuation of the inner conductor of one section of aconcentric transmission line which is connected to a second matchedsection of line of smaller diameter. The matching is accomplished byappropriate design of the two sections of line.

Fig. 2a is a cross section on the line a-a, Fig. 2.

Fig. 3 shows another form which my system may take.

Fig. '3a is a cross section on the line a--a, Fig. 3.

Fig. 4 shows a still .tion.

further form of my inven- Fig; 5 shows schematically a system foroperating the antenna by gas under pressure.

Fig. 6 illustrates a metal piston operating in an insulating cylinder,which is physically a prolongation of the outer conductor.

In Figs. 1, 2 and 3 adjustment of the radiator is accomplished byvariation of gas pressure in the transmission line so as tormove apiston which is fixed to the radiator element. In Fig. 4 a gas pressureoperated motor turns a screw which in turn moves the radiator to thedesired position.

Fig. 5 shows one form which the input end of the transmission line maytake in supplying electrical energy and gas pressure to the antennas ofFigs. 1 and 2.

In Fig. 1 I show a movable tubular radiator element I having aflixed atone end a piston 2 of electrical insulating materialhaving packing rings3 which wipe the inside surface of the outer conductor 4 of a concentrictransmission line 4-5 having an inner conductor 5.

Radiator I slides freely over the inner conductor 5 of the transmissionline. The transmission line is terminated physically with an insulatingspacing member 6 having a packing ring 1 for keeping out water. Pressure,of gas applied between the inner and outer conductors of transmissionline 4-5 moves radiator I and piston 2 against helical spring 8 whichserves to lower the radiator element I when the gas pressure is reduced.Spring loaded valve 9 may be provided to maintain atmospheric pressurein the spaces above piston 2, although this is not essential since thegas in these spaces may be compressed or expanded according to theposition of the piston 2.

Fig. 6 shows an alternative form of construction in which the outerconductor la of transmission line la-5a is terminated in a cylinder ofinsulating material in which the piston 2a oper-. ates. Suchconstruction makes it possible to use a metallic piston 2a in lieu ofthe insulated piston 2 required in Fig. 1.

The radiating portion of this form of antenna is that which extendsbeyond the outer conductor of the transmission line. Thus, in Fig. 1,dimension X represents the length of the radiating portion, whereasdimension Y in Fig. 6 gives the length of the radiator.

In order that the electrical load resistance represented by the radiatorwill be of the correct value so that reflection of electrical energywill not take place at the junction of the radiator and transmissionline, it is essential that the.

antenna or radiator resistance be matched with that of the line. Thecharacteristic impedance of a transmission line operated at the highfrequencies employed in radio is in the nature of a resistance. Toefiiciently match a radiator to such a line without recourse toauxiliary apparatus, requires that a resonant radiator be employed. Inthat form of my invention shown in Figs. 1 and 6, proper impedancematching requires that the length of the radiator be an odd number ofquarter wave lengths. As the length of the radiator becomes a criticalfunction of frequency for a proper match to the line, close adjustmentof radiator length is required. As my system is of the continuouslyvariable type and capable of close adjustment to any length withindesigned limits, and as this adjustment can be made from a distance withlittle auxiliary apparatus it has advantages not known to exist in priorsystems.

Fig. 2 shows another form of my invention in which the radiator elementI I is operated against the tension of spring I2 by gas pressure appliedto the inside of inner conductor I3 of transmission line l3!4.Transmission line I3I4 is terminated physically at both ends by gastight insulating members I5 and I6. At I1 is shown a spacing insulatorfor concentric line I3--I l. Packing rings are shown at I8 to preventthe escape of gas.

A second section of concentric transmission line is' shown having innerconductor I9 and outer conductor 2!]. The outside diameters of innerconductors I3 and I9 are so proportioned to the inner diameters of theouter conductors I 4 and 20 that the characteristic impedances of thetwo sections of line are equal. Spacing between the two connectingconductors 2I and 22 is also determined to yield this samecharacteristic impedance in order that electrical reflections at thisjunction will be a minimum.

Gas pressure for raising and lowering radiator II is applied through thespace between conductors I9 and 2G, thence through channel 23 ininsulator I8 to the inside of tubular conductor I3.

At Fig. 2a is shown a sectional view showing ground plane conductors 24which take the form of wires extending from the upper end of conductorM.

Fig. 3 shows another form which my antenna may take. This comprises ametallic cylinder 25 mounted upon an insulator 26. A movable conductor2? having a piston 28 with piston rings 29 in combination with cylinder25 and that portion 3% of concentric transmission line 3Il3I whichextends above the outer conductor 3| of the transmission line, comprisethe radiating portion of the system.

In that form of my invention shown in Fig. 3, I move the rod 21 up ordown by applying gas pressure to both sides of piston 28. Conductor 30of the transmission line is of hollow tubular construction for applyingpressure to the lower side of piston 28. Pressure is also appliedthrough the space between conductors 3i] and 3|, thence throughelectrically insulating tube 32 to. the upper end of cylinder 25. Inthis manner, piston 28 and rod 21 may be adjusted to any desiredposition. A stuffing box 33 at the upper end of cylinder 25 preventsleakage of gas.

In Fig. 4 is shown a still further modified form of my invention havinga concentric transmission 1ine3 .35 with a hollow inner conductor 34-and tubular out-en conductor 35 for applying gas through either tube toa turbine engine device having a fixed nozzle disc 3i: of insulatingmaterial affixed to the outer conductor 35 of transmission line 34-35.The rotary portion of the turbine comprises rotor 31 of insulatingmaterial affixed to the hollow shaft 38 and screw 39 which engages theradiating member 43 for raising or lowering same to the desiredposition. The remaining portion of the system comprises ports All inshaft 38 and thrust block 42 of insulating material which also acts as atransmission line spacer.

The turbine Its-3'! is of the reversible type to permit rotation ineither direction according to which direction the gas pressure isapplied. It will be understood that the turbine may be located outsidethe transmission line and may take any suitable form of construction.Moreover, it may be replaced by a reciprocating engine device withoutdeparting from the spirit of my invention.

At 43 is an insulating member of appropriate construction for sealingthe system against the entrance of moisture or escape of gas at thatpoint. The radiator it has a conductive connection through screw 39 andshaft 38 to the inner conductor 34 of transmission line 3-t35. Inantenna systems of this type, the radiating portion is that conductingpart which extends in space above the other or outer conductor of thetransmission line, as previously mentioned.

Fig. 5 shows the output portion of the final stage of a radiotransmitter 44 having an amplifying tube 45 the anode 46 of which isconnected to an output circuit ii-48 to a high voitage source it througha current indicating device The output circuit is coupled or connectedto the inner conductor 55 of concentric transmission line til-52. Outerconductor 52 is shown grounded at 53.

Transmission line 5I52 is sealed gas tight by an insulating device 54.Means are provided by valve 35 for admitting gas from tank 59 to thetransmission line 5I52 for varying the pressure in the line to adjustthe height of the antennas of Figs. 1 and 2. Pressure indicating means56 may be calibrated in terms of antenna height. Final adjustment ofantenna height is most effectively accomplished by noting the reading ofcurrent indicating device as the length of the antenna is changed. Analternative source of gas is shown by pipe connection 5! through valve58.

I have found it desirable to use dry compressed nitrogen or carbondioxide as a gas. Any dry gas or even an insulating liquid may beemployed if desired. The term fluid will be understood to apply to anysuitable gas or liquid.

If it is desired to employ an open type of transmission line in lieu ofa concentric line, one or more conductors of the line may be made oftubular construction for applying the gas pressure.

While I have described my invention in certain preferred embodiments, itwill be understood that 'modificatiohs may be made, and that nolimitations are intended other than those imposed by the scope of theappended claims.

The invention herein described and claimed may be used and/ormanufactured by or for the Government of the United States of Americafor governmental purposes without the payment of any royalties thereonor therefor.

What I claim as new and desire to secure by Letters Patent in the UnitedStates is as follows:

1. An antenna system including a high frequency transmission line havingtwo concentric conductors at least one of which is tubular, a radiatingelement mounted in, electrically connected to and projecting from saidtubular conductor to transfer electric currents between said tubularconductor and said element, said element being sufliciently rigid to beself-supporting and free at its outer end and arranged to slide in saidconductor; in a fluid-tight manner, and means for applying fluidpressure to said tubular conductor whereby the effective length of saidradiating element may be adjusted to selected values to respondefi'iciently to different Wave lengths.

2. An antenna system including a concentric high frequency transmissionline having a tubular outer member, a radiating element projecting fromand mounted in said tubular member and electrically connected thereto totransfer electric currents between said tubular member and said element,said element being sufficiently rigid to be self-supporting and free atits outer end and arranged to slide in said member in a fluid-tightmanner, and means for applying fluid pressure to said tubular memberwhereby the effective length of said radiating element may be adjustedto selected values to respond to different wave lengths.

tight manner, and means for supplying fluid pressure to said tubularconductor wherein said element is mounted to change the effective lengthof said element to selected values to respond efiiciently to differentwave lengths.

4. An antenna system including a high frequency transmission line havingat least one tubular conductor, a source of gas under pressure having agas connection to said tubular condoctor, an (antenna element projectingfrom said tubular conductor, a screw engaging said antenna element andmeans for turning said screw, said means comprising a gas driven enginedevice contained within said tubular conductor whereby the eflectiveimpedance of said antenna element may be adjusted to a valuesubstantially equal to the surge impedance of said transmission line.

5. An antenna system comprising a high frequency transmission linehaving at least one tubular conductor, a! tubular radiating elementprojecting irom said tubular conductor, said element being free at itsouter end and sufficiently rigid to be self-supporting, a motor drivefor adjusting the length of said radiating element and remotelycontrollable means for supplying power axially through said tubularconductor to operate said motor drive.

6. An antenna system comprising a high frequency transmission linehaving at least one hollow conductor, a tubular radiating elementprojecting from said hollow conductor, said element being free at itsouter end and sufficiently rigid to be self-supporting, a motor drivefor varying the length of said radiating element, said motor drive bengwholly'conta-ined within said hollow conductor, and remotelycontrollable means for supplying power longitudinally through saidhollow conductor to operate said motor drive.

JENNINGS B. DOW.

